Apple Sign In “invalid_client”, signing JWT for authentication using PHP and openSSL
As indicated here, the problem is actually in the signature generated by openSSL. Using ES256, the digital signature is the concatenation of two unsigned integers, denoted as R and S, which are the result of the Elliptic Curve (EC) algorithm. The length of R || S is 64. The openssl_sign function generates a signature which … Read more